+from UserDict import DictMixin
+
from django import forms
-from django.db import models
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes import generic
from django.core.exceptions import ObjectDoesNotExist
from django.core.validators import RegexValidator
+from django.db import models
from django.utils import simplejson as json
from django.utils.encoding import force_unicode
+from mptt.models import MPTTModel, MPTTModelBase, MPTTOptions
+
from philo.exceptions import AncestorDoesNotExist
from philo.models.fields import JSONField
-from philo.utils import ContentTypeRegistryLimiter, ContentTypeSubclassLimiter
from philo.signals import entity_class_prepared
+from philo.utils import ContentTypeRegistryLimiter, ContentTypeSubclassLimiter
from philo.validators import json_validator
-from UserDict import DictMixin
-from mptt.models import MPTTModel, MPTTModelBase, MPTTOptions
class Tag(models.Model):